Sand-bending Exhaust Tube

i think for the time effort it would take to sand bend a set of headers you could build a manual mandrel bender, heres what is ment by mandrel bending for those who do not know allready,
http://www.muffler-tech.com/mandrel_bending.htm
the mandrel shown is for a very tight bend, a larger radius would only require plug mandrel, heres another site showing different mandrels, http://www.toolsforbending.com/mandrels.asp
i built my own hydraulic mandrel bender.

 

If you use sand and water along with a cheap hydraulic bender you don't need to use heat at all. The water makes the sand so dense the pipe won't kink. Just think about how much dry sand moves about under your feet on the beach compared to wet sand.

 

Just do sh*tty welds on the end and the explosion risk is gone. You can't put enough instantaneous heat in with a torch, so any water turning to steam will push out the holes. Heck, the holes can let individual grains of sand thru and still work just fine.

With all the effort in taping sure sounds easier to mig caps on both ends and just leave em a little long.

Electric palm sanders held to the tubing can help the tamping process along.

 

Early Sixties, out in the middle of the ocean aboard a Navy ship, when I had to bend pipe,( No benders) always used sand and a rose bud torch, , most of the time two. and one shaping..All different sizes of pipe..
Duane..

 

i can sell you bends cheep!

 

That's interesting. I'd like to see some photos of the bender you built if you have any.

What centerline radius would qualify as a very tight bend? For example, could you bend 2.25" exhaust tubing on a 4.75" radius with just a plug-style mandrel?

 

ok, i didnt know we were putting a water tight seal on the caps, theres no reason for that. the sand is just packed in to keep the shape while bending, so a water tight seal isnt needed, as long as yer sand aint pourin out. yes, as posted about sweating pipe w water in it, its a no go. youd never get it capped to blow up, unless you used a threaded cap of sorts.

 

I found this vid on youtube. This guys packs the tubing with sand/water, seals both ends with duct tape and bends in a HF pipe bender. Looks simple enough for only a few bends.
http://www.youtube.com/watch?v=GWT3N3m4bE4&feature=related

 

An older wiser dude bent the roll cage for our front engine dragster using silica sand in the pipe and hammered on frost plugs on the ends, with an armstrong bender (similar to a conduit bender) no heat, no water. Knocked the plugs off the ends dump the sand and you would fool alot of people how it was done, looked excellent.

 

Yeah, clean/dry sand and gentle heat will work, I dont believe the ends need to be capped water tight but they should well capped.
For beginners bigger bends maybe your limit any ways machine bends can be purchased for the tight/special/complex bends.

 

heres a couple of pics of the bender i made, its powered but for header tubing it could be manual, i made myself a formed end mandreal to use in 1-1/2" stainless 1/16" wall tubing with a 6" radius, all told i may have $2000 into this machine, there is a formula for what type of mandrel to use with what size pipe at a specific radius, you can get the info from mandrel tooling supplier.

 

there was an article in an American Rodder about sandbending tubing. They caped one end with a welded plate, packed in dry sand then made a wooden plug and pounded it into the other end.

I would just have welded plates on each end and the welds do not have to be perfect. Just enough the hold the caps on and still be able to vent out any steam you might get. All you really want to do is keep the grains of sand from coming out.

They do make COOL radiator hoses (tubes really). But it really helps to flare the ends slightly or bead roll the ends and use short rubber ends. The flare or bead roll keeps the tube from popping off the rubber ends under pressure.

 

Anyone have any pics of tight sand bent exhaust?

 

If you cap the tubes,and use dry sand,that has to be packed well,heat the tube till it is red hot and bend it around a buck.It will not kink.It acually works really nice,but it is not the fastest way to bend tube.Good luck.

 

These are pretty tight bends.
About as tight as the small radius U-bends you can buy...

 

I worked on a Formula Ford header that was sand bent, I was told the English chap who made it used a charcoal blacksmith's forge for heat.

I've used sand inside cold tubing in my Hossfeld when the tubing just slightly tended to kink, to help things along. I used sandblasting sand, and it seems to pack itself. Once I pour it in, further tamping, shaking, etc does very little. I just shove a rag or shop wipe in each end to hold it in place.

I'm going to try the wet sand trick sometime to see how it works, I've never had luck with SS tubing in the Hossfeld, maybe that will help.

 

I was starting some in an ordinary bender sand packed with a big bolt for compression and decided to try one extra tight, it bent okay for a couple of inches and then did a series of perfectly spaced convolutions I could only put down to it being packed too tight.

 

Too tight and too thin of wall

 

This is neat, can this process be used to build stainless headers? I was thinking the stainless may be too hard, or not. I'm sure one of you guy's know.

 

I have seen plenty of pictures of larger radius exhaust that have been sand bent, but still have not seen any pics of tight radius sand bent exhaust (like headers) that look any good.

 

A guy i know did it some on a drag harley

 

I'm just curious how you make a template for something like this? I need to bend some for my exhaust but don't wanna pay someone.

I thought about buying some of the hot air tubing, you know that corrugated stuff that attaches to mid 70's/80's air cleaners for a template.

 

Root........, I am reaching here, but I believe it was 4 to 6 years ago, in Street Rodder, there was an article on this very thing...................Corrugated alumimum hot air tube, and a can of expanding foam to "stiffen" it all up after you get the layout, box it up, and send it to them.............................They send the tubing / exhaust system back to you, all bent up and ready to weld....

Happy hunting

 

When I was in the Navy, that was the only way I bent pipe was with sand and a rose bud tip. Made templets from plate cut to what degree I wanted the pipe bent, welded flat bar around the degree of the bend or angle iron that was ,bent to shape and welded..
Duane.

 

I found this recently. Not sure it's relevant to sand bending, and I'm afraid to ask the price, but it looks neat, and it obviously took some thought.

http://icengineworks.com/icewmain.htm

 

I watched a piece on How It's Made a while back and they were bending either copper of aluminum tubing to for a condenser coil. The filled the tube with water then froze it prior to bending. Obviously it would only work for Cold Bending on softer materials.

 

Ihave a Huth exhaust bender in my shop. When I need to make a large bend on stainless steel exhaust tube I have to fill it with sand and weld the ends or it will kink like hell. I also wrap the tube with newspaper so it slides over the dies. Not mandrel quality, but pretty good for what it is.

 

When my son was racing karts we made a few sand bent headers for the B&S motors he ran.
I used dry play sand and plugged both ends of the tube with wooden dowels.
Never had any problems...used the rosebud to heat to dull red...some I pulled freehand...a couple I partially wrapped around large dia. tubing to get the desired bend.

 

What Duane said...old pipefitter's technique; prolly dates back to turn of the last century...slide